1. Field of the Invention
The field of the invention concerns the area of medical imaging, particularly mammography.
2. Description of Related Art
Tomosynthesis is a variant of conventional planar tomography in which a limited number of radiographic projections of a patient's body organ is acquired in digital form at different angles relative to the patient. All the projections acquired from the different angles are then processed to obtain three-dimensional data on said patient organ. These three-dimensional data can be displayed as a set of sectional planes or in any other three-dimensional form.
Currently known tomosynthesis devices for mammography comprise an arm 15 carrying a radiation source 14 capable of emitting radiation, a radiation detector 17 capable of receiving the radiation, a planar support surface 26 for the object placed between the source 14 and the detector 17, a plate 74 placed between the object support surface 26 and the source 14 to compress the object 16 to be imaged, and processing means 32. The arm 15 carrying the source 14 can be moved about a first axis 19 in a plurality of positions 7. This arm 15 acts as positioner. The source is pivot-mounted on the arm to so that it can be oriented with respect to the object support surface. These movements of the source and arm about their respective rotation axes allow the radiographic projections of the breast 16 of the patient to be acquired at different angles during a sequence of radiation exposures.
The breast 16 is placed on the object support surface 26 so that the detector 17 can receive radiation which has passed through the inner structures of the breast 16. The detector 17 produces a signal which is processed by the processing means 32 to produce a radiographic projection of the inner structures of the breast 16. The arm 15 is then moved to a new position 7 to produce a radiographic view at a different angle, and so on. Using reconstruction techniques, all the radiographic projections are able to produce three-dimensional data of the breast 16.
One limitation specific to the above-described method is that the information used to reconstruct three-dimensional data may be incomplete outside a volume determined by the acquisition geometry. Existing systems do not provide any information to the user indicating beforehand whether the entirety of the structures of interest of the object can be reconstructed with nominal quality.
The purpose of the invention is therefore to propose a device and method to assist the user in the identification of anomalies in the imaged region, by providing information on the zone for which three-dimensional data of nominal quality will be obtained.